A passive optical network (PON) technology is a point-to-multipoint fiber access technology. With continuous development of technologies, an EPON (Ethernet Passive Optical Network), a GPON (Gigabit passive Optical Network), an NG PON (next generation PON), and the like emerge. To ensure network reliability, a PON network needs to support fast switching. FIG. 1 shows a PON network architecture, which includes a first OLT 10 (Optical Line Terminal), a second OLT 12, an ODN (Optical Distribution Network), and ONUs (Optical Network Unit). When the first OLT 10 serves as an active OLT, a feeder fiber between an active port on the first OLT 10 and the ODN is an active feeder fiber, and a feeder fiber between a standby port on the second OLT 12 and the ODN is a standby feeder fiber. In a case in which the active feeder fiber or the active port is faulty, switching to the standby port needs to be performed to recover a service and implement protection for the feeder fiber.
In order to further extend application of the PON, a time wavelength division multiplexing-passive optical network (TWDM-PON) is put forward in the industry. The TWDM-PON is a passive optical network that combines both WDM and TDM technologies, and includes an office-side OLT, a user-side ONU or ONT (optical network terminal), and an ODN.
When a feeder fiber between the OLT and the ODN or a working port of the optical line terminal is faulty and this leads to interruption of communication between the optical line terminal and the optical network unit, no specific solution has yet been given for the TWDM-PON system, which is also an urgent issue that currently needs to be solved in the TWDM-PON system.